Cisco 350-501 Practice Test 25
Question 240
For an original SPCOR service-provider engineering scenario, consider: A route reflector sends only its selected path and edge routers lose backup path visibility even though operators expect Add-Paths diversity. Select TWO complementary steps: the targeted correction and its strongest prechange validation.
- Change: Apply supported consistent metric style and tune link costs to the provider's intended shortest-path and capacity policy.
- Check: Inspect negotiated additional-path capability, backup path RIB and FIB entries and forwarding interruption during simulated failure.
- Change: Enable compatible path diversity or BGP PIC mechanisms where supported and verify backup data-plane programming before a failure.
- Check: Trace a known client flow through DNS resolution, IPv4 or IPv6 encapsulation, translator bindings and return path with packet captures.
- Assume any BGP neighbor automatically accepts multiple path identifiers and every backup route is preprogrammed without feature support.
Explanation
Correct Answer
B:Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures. Required intervention: Enable compatible path diversity or BGP PIC mechanisms where supported and verify backup data-plane programming before a failure.
C:Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures. Acceptance: Valid alternate paths are visible and traffic shifts within expected service objectives when the primary next hop fails.
Incorrect Answers
A:Change: Apply supported consistent metric style and tune link costs to the provider's intended shortest-path and capacity policy. Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures.
D:Check: Trace a known client flow through DNS resolution, IPv4 or IPv6 encapsulation, translator bindings and return path with packet captures. Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures.
E:For this select two assessment, the shortcut changes or bypasses the necessary routing, service or operational boundary rather than correcting it. Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures.
Question 241
A service provider network engineer is reviewing this backbone or customer-service scenario: A PE with many customer VPN routes experiences slow restoration after a core failure because it lacks precomputed backup next-hop forwarding behavior. A proposed shortcut is: Assume any BGP neighbor automatically accepts multiple path identifiers and every backup route is preprogrammed without feature support. What should the service provider engineer recommend as the narrowly scoped correction? Select ONE best answer.
- Tune consistent OSPF cost or reference-bandwidth settings and validate reconvergence under controlled link failures.
- Enable compatible path diversity or BGP PIC mechanisms where supported and verify backup data-plane programming before a failure.
- Assume any BGP neighbor automatically accepts multiple path identifiers and every backup route is preprogrammed without feature support.
- Select single- or multi-topology IS-IS according to dual-stack forwarding requirements and verify both address-family reachability and advertised topology data.
Explanation
Correct Answer
B:This targeted action addresses the observed service-provider control or forwarding gap without discarding necessary controls. Applied case: A PE with many customer VPN routes experiences slow restoration after a core failure because it lacks precomputed backup next-hop forwarding behavior.
Incorrect Answers
A:Tune consistent OSPF cost or reference-bandwidth settings and validate reconvergence under controlled link failures. Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures.
C:Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures. Use this instead: Enable compatible path diversity or BGP PIC mechanisms where supported and verify backup data-plane programming before a failure.
D:Select single- or multi-topology IS-IS according to dual-stack forwarding requirements and verify both address-family reachability and advertised topology data. Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures.
Question 242
A Cisco service provider design review finds: A PE with many customer VPN routes experiences slow restoration after a core failure because it lacks precomputed backup next-hop forwarding behavior. The team proposes: Enable compatible path diversity or BGP PIC mechanisms where supported and verify backup data-plane programming before a failure. Which engineering principle most strongly supports the recommended response? Select ONE best answer.
- Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures.
- Single topology shares reachability assumptions across enabled families, while multi-topology can maintain distinct IPv4 and IPv6 topology information.
- Redistribution changes protocol scope and metrics; uncontrolled mutual redistribution can create loops and excessive IGP state.
- OSPF area types control which LSA classes are accepted while ABRs can summarize routes; a summary may hide unavailable more-specifics if chosen carelessly.
Explanation
Correct Answer
A:Demonstrable success requires: Valid alternate paths are visible and traffic shifts within expected service objectives when the primary next hop fails. Applied case: A PE with many customer VPN routes experiences slow restoration after a core failure because it lacks precomputed backup next-hop forwarding behavior.
Incorrect Answers
B:Single topology shares reachability assumptions across enabled families, while multi-topology can maintain distinct IPv4 and IPv6 topology information. Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures.
C:Redistribution changes protocol scope and metrics; uncontrolled mutual redistribution can create loops and excessive IGP state. Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures.
D:OSPF area types control which LSA classes are accepted while ABRs can summarize routes; a summary may hide unavailable more-specifics if chosen carelessly. Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures.
Question 243
The service provider operations team has not yet approved a change. Current evidence indicates: A PE with many customer VPN routes experiences slow restoration after a core failure because it lacks precomputed backup next-hop forwarding behavior. Which evidence best tests the technical diagnosis before approving a disruptive change? Select ONE best answer.
- Check neighbor state transitions, interface MTU, hello and dead intervals, area type and network type on both peers.
- Trace a known client flow through DNS resolution, IPv4 or IPv6 encapsulation, translator bindings and return path with packet captures.
- Inspect negotiated additional-path capability, backup path RIB and FIB entries and forwarding interruption during simulated failure.
- Measure neighbor resets, stale route retention, forwarding counters and route processing after a planned RP switchover.
Explanation
Correct Answer
C:Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures. Applied case: A PE with many customer VPN routes experiences slow restoration after a core failure because it lacks precomputed backup next-hop forwarding behavior.
Incorrect Answers
A:Check neighbor state transitions, interface MTU, hello and dead intervals, area type and network type on both peers. Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures.
B:Trace a known client flow through DNS resolution, IPv4 or IPv6 encapsulation, translator bindings and return path with packet captures. Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures.
D:Measure neighbor resets, stale route retention, forwarding counters and route processing after a planned RP switchover. Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures.
Question 244
A candidate correction has been tested and the platform team requires a post-change acceptance check. Original problem: A PE with many customer VPN routes experiences slow restoration after a core failure because it lacks precomputed backup next-hop forwarding behavior. The carrier operations owner needs positive and negative tests showing existing customer services remain available. Which acceptance result demonstrates correct service provider forwarding and control behavior without disrupting authorized workflows? Select ONE best answer.
- Valid alternate paths are visible and traffic shifts within expected service objectives when the primary next hop fails.
- Intended EBGP adjacencies establish securely and exchange only approved prefixes in the selected address family.
- The intended Level-1 or Level-2 adjacency forms and the routers exchange consistent link-state information without dropping required hello traffic.
- Only policy-matched routes change forwarding or advertisement behavior and customer communities have their documented effect.
Explanation
Correct Answer
A:Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures. The result must be validated using the documented device, service or access context.
Incorrect Answers
B:Intended EBGP adjacencies establish securely and exchange only approved prefixes in the selected address family. Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures.
C:This option addresses a different service provider engineering topic (IS-IS neighbor adjacency and link readiness) rather than the documented BGP Additional Paths PIC and fast failover decision.
D:Only policy-matched routes change forwarding or advertisement behavior and customer communities have their documented effect. Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures.
Question 245
An implementation sign-off request identifies the following problem: A PE with many customer VPN routes experiences slow restoration after a core failure because it lacks precomputed backup next-hop forwarding behavior. Which paired technical change and validation should close the implementation review? Select ONE best answer.
- Change: Verify aggregation protocol, member compatibility, hashing expectations and actual active bandwidth before designing redundancy or QoS. Verify: Inspect member actor and partner state, bundle hashing, counters and traffic distribution under several representative flows.
- Change: Diagnose the affected protocol's actual session prerequisites and advertisement scope before changing unrelated routing controls. Verify: Compare per-protocol neighbor state, error messages, encapsulation, path reachability, authentication and interface counters.
- Change: Apply supported consistent metric style and tune link costs to the provider's intended shortest-path and capacity policy. Verify: Review link metric TLVs, enabled metric style, SPF database and before-after path selection for two candidate routes.
- Change: Enable compatible path diversity or BGP PIC mechanisms where supported and verify backup data-plane programming before a failure. Verify: Inspect negotiated additional-path capability, backup path RIB and FIB entries and forwarding interruption during simulated failure.
Explanation
Correct Answer
D:Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures. The change is successful only when: Valid alternate paths are visible and traffic shifts within expected service objectives when the primary next hop fails.
Incorrect Answers
A:Change: Verify aggregation protocol, member compatibility, hashing expectations and actual active bandwidth before designing redundancy or QoS. Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures.
B:Change: Diagnose the affected protocol's actual session prerequisites and advertisement scope before changing unrelated routing controls. Add-Paths can advertise multiple BGP paths under negotiated capability while PIC accelerates convergence using preinstalled repair or next-hop structures.
C:Change: Apply supported consistent metric style and tune link costs to the provider's intended shortest-path and capacity policy. A PE with many customer VPN routes experiences slow restoration after a core failure because it lacks precomputed backup next-hop forwarding behavior.
Question 246
A service provider network engineer is reviewing this backbone or customer-service scenario: An IOS XR route-policy is written like an IOS XE route-map and never passes the intended set of customer prefixes. A proposed shortcut is: Copy a route map verbatim into IOS XR policy syntax and assume it preserves implicit deny and pass behavior. What should the service provider engineer recommend as the narrowly scoped correction? Select ONE best answer.
- Diagnose the affected protocol's actual session prerequisites and advertisement scope before changing unrelated routing controls.
- Coordinate BFD with supported routing clients and realistic detect-multiplier and interval settings for stable rapid failure detection.
- Copy a route map verbatim into IOS XR policy syntax and assume it preserves implicit deny and pass behavior.
- Use the platform's supported policy language, explicit prefix sets and match sequencing to permit only intended routes and apply actions at the correct direction.
Explanation
Correct Answer
D:This targeted action addresses the observed service-provider control or forwarding gap without discarding necessary controls. Route filtering is an ordered policy decision with platform-specific syntax and implicit outcomes; bad matching or direction can leak or drop routes.
Incorrect Answers
A:Diagnose the affected protocol's actual session prerequisites and advertisement scope before changing unrelated routing controls. Route filtering is an ordered policy decision with platform-specific syntax and implicit outcomes; bad matching or direction can leak or drop routes.
B:Coordinate BFD with supported routing clients and realistic detect-multiplier and interval settings for stable rapid failure detection. Route filtering is an ordered policy decision with platform-specific syntax and implicit outcomes; bad matching or direction can leak or drop routes.
C:Route filtering is an ordered policy decision with platform-specific syntax and implicit outcomes; bad matching or direction can leak or drop routes. For this best change assessment, the shortcut changes or bypasses the necessary routing, service or operational boundary rather than correcting it.
Question 247
A Cisco service provider design review finds: An IOS XR route-policy is written like an IOS XE route-map and never passes the intended set of customer prefixes. The team proposes: Use the platform's supported policy language, explicit prefix sets and match sequencing to permit only intended routes and apply actions at the correct direction. Which engineering principle most strongly supports the recommended response? Select ONE best answer.
- Redistribution changes protocol scope and metrics; uncontrolled mutual redistribution can create loops and excessive IGP state.
- Route filtering is an ordered policy decision with platform-specific syntax and implicit outcomes; bad matching or direction can leak or drop routes.
- OSPFv3 neighbors commonly use IPv6 link-local transport while routing advertisements and instances depend on the enabled topology and area.
- OSPF area types control which LSA classes are accepted while ABRs can summarize routes; a summary may hide unavailable more-specifics if chosen carelessly.
Explanation
Correct Answer
B:Relevant validation before approval: Evaluate a test table with allowed, denied and boundary prefixes against actual show-policy and BGP advertised-routes evidence. Demonstrable success requires: Authorized prefixes are imported or exported and unintended customer or infrastructure prefixes are rejected without adjacency disruption.
Incorrect Answers
A:Redistribution changes protocol scope and metrics; uncontrolled mutual redistribution can create loops and excessive IGP state. Route filtering is an ordered policy decision with platform-specific syntax and implicit outcomes; bad matching or direction can leak or drop routes.
C:OSPFv3 neighbors commonly use IPv6 link-local transport while routing advertisements and instances depend on the enabled topology and area. Route filtering is an ordered policy decision with platform-specific syntax and implicit outcomes; bad matching or direction can leak or drop routes.
D:OSPF area types control which LSA classes are accepted while ABRs can summarize routes; a summary may hide unavailable more-specifics if chosen carelessly. Route filtering is an ordered policy decision with platform-specific syntax and implicit outcomes; bad matching or direction can leak or drop routes.
Question 248
The service provider operations team has not yet approved a change. Current evidence indicates: An IOS XR route-policy is written like an IOS XE route-map and never passes the intended set of customer prefixes. Which evidence best tests the technical diagnosis before approving a disruptive change? Select ONE best answer.
- Compare valid path candidates and detailed BGP attributes under a test prefix, then trace which decision criterion breaks the tie.
- Trace sample source routes, redistribution policy hits, tags, LSDB or LSP size and resulting RIB changes across both boundaries.
- Evaluate a test table with allowed, denied and boundary prefixes against actual show-policy and BGP advertised-routes evidence.
- Check route-reflector client relationships, originator and cluster attributes, BGP next-hop resolution and the RIB versus FIB.
Explanation
Correct Answer
C:Route filtering is an ordered policy decision with platform-specific syntax and implicit outcomes; bad matching or direction can leak or drop routes. If confirmed, the proportionate intervention is: Use the platform's supported policy language, explicit prefix sets and match sequencing to permit only intended routes and apply actions at the correct direction.
Incorrect Answers
A:Compare valid path candidates and detailed BGP attributes under a test prefix, then trace which decision criterion breaks the tie. Route filtering is an ordered policy decision with platform-specific syntax and implicit outcomes; bad matching or direction can leak or drop routes.
B:Trace sample source routes, redistribution policy hits, tags, LSDB or LSP size and resulting RIB changes across both boundaries. Route filtering is an ordered policy decision with platform-specific syntax and implicit outcomes; bad matching or direction can leak or drop routes.
D:Check route-reflector client relationships, originator and cluster attributes, BGP next-hop resolution and the RIB versus FIB. Route filtering is an ordered policy decision with platform-specific syntax and implicit outcomes; bad matching or direction can leak or drop routes.
Question 249
A candidate correction has been tested and the platform team requires a post-change acceptance check. Original problem: An IOS XR route-policy is written like an IOS XE route-map and never passes the intended set of customer prefixes. The carrier operations owner needs positive and negative tests showing existing customer services remain available. Which acceptance result demonstrates correct service provider forwarding and control behavior without disrupting authorized workflows? Select ONE best answer.
- Steering influences targeted peers as expected while reachability is preserved when remote policy ignores the hint.
- Authorized prefixes are imported or exported and unintended customer or infrastructure prefixes are rejected without adjacency disruption.
- Both address families receive valid advertised next hops for the chosen topology mode and failures are diagnosed per family.
- The intended Level-1 or Level-2 adjacency forms and the routers exchange consistent link-state information without dropping required hello traffic.
Explanation
Correct Answer
B:Route filtering is an ordered policy decision with platform-specific syntax and implicit outcomes; bad matching or direction can leak or drop routes. The approved implementation step was: Use the platform's supported policy language, explicit prefix sets and match sequencing to permit only intended routes and apply actions at the correct direction.
Incorrect Answers
A:Steering influences targeted peers as expected while reachability is preserved when remote policy ignores the hint. Route filtering is an ordered policy decision with platform-specific syntax and implicit outcomes; bad matching or direction can leak or drop routes.
C:Both address families receive valid advertised next hops for the chosen topology mode and failures are diagnosed per family. Route filtering is an ordered policy decision with platform-specific syntax and implicit outcomes; bad matching or direction can leak or drop routes.
D:The intended Level-1 or Level-2 adjacency forms and the routers exchange consistent link-state information without dropping required hello traffic. Route filtering is an ordered policy decision with platform-specific syntax and implicit outcomes; bad matching or direction can leak or drop routes.
Question 250
For an original SPCOR service-provider engineering scenario, consider: An IOS XR route-policy is written like an IOS XE route-map and never passes the intended set of customer prefixes. Select TWO complementary steps: the targeted correction and its strongest prechange validation.
- Check: Evaluate a test table with allowed, denied and boundary prefixes against actual show-policy and BGP advertised-routes evidence.
- Change: Use the platform's supported policy language, explicit prefix sets and match sequencing to permit only intended routes and apply actions at the correct direction.
- Copy a route map verbatim into IOS XR policy syntax and assume it preserves implicit deny and pass behavior.
- Check: Compare area LSDB LSA types, ABR summaries, default injection and actual endpoint reachability for inside and outside addresses.
- Change: Troubleshoot OSPF network type, area, neighbor timers, authentication and database-exchange parameters before modifying routing advertisements.
Explanation
Correct Answer
A:Route filtering is an ordered policy decision with platform-specific syntax and implicit outcomes; bad matching or direction can leak or drop routes. Required intervention: Use the platform's supported policy language, explicit prefix sets and match sequencing to permit only intended routes and apply actions at the correct direction.
B:Route filtering is an ordered policy decision with platform-specific syntax and implicit outcomes; bad matching or direction can leak or drop routes. Evidence: Evaluate a test table with allowed, denied and boundary prefixes against actual show-policy and BGP advertised-routes evidence.
Incorrect Answers
C:For this select two assessment, the shortcut changes or bypasses the necessary routing, service or operational boundary rather than correcting it. Route filtering is an ordered policy decision with platform-specific syntax and implicit outcomes; bad matching or direction can leak or drop routes.
D:Check: Compare area LSDB LSA types, ABR summaries, default injection and actual endpoint reachability for inside and outside addresses. Route filtering is an ordered policy decision with platform-specific syntax and implicit outcomes; bad matching or direction can leak or drop routes.
E:Change: Troubleshoot OSPF network type, area, neighbor timers, authentication and database-exchange parameters before modifying routing advertisements. Route filtering is an ordered policy decision with platform-specific syntax and implicit outcomes; bad matching or direction can leak or drop routes.
